From Philadelphia sportswriter Tiny Maxwell neglecting Ty Cobb’s advice in the early 1920s to “buy Coca-Cola stock for sure,” to Time planting Amazon.com CEO Jeff Bezos on its cover just in time for the dot-com crash: Journalists’ stock market calls aren’t always spot on.

But it may be when both wildly bullish and bearish stories start getting published that investors should really duck for cover.

In a recent analysis, economists Michal Dzielinski and Henrik Hasseltoft sifted through millions of news stories on S&P 500 companies published during the decade ending in 2012 and scored by a Thomson Reuters linguistic analysis for “news tone.” They found that when news tone was particularly disperse, with significantly positive and negative stories getting published, this was associated with greater disagreement among investors–and higher rates of stock market turnover.

The bad news won out. A one standard deviation increase in news tone dispersion—meaning a significant swing away from the average–was predictive of a drop in stock returns relative to normal expectations. And the shortfall is meaningful, at between four and five percentage points over the next three to six months. Bad news indeed.